Centrifuge tube closure assembly

ABSTRACT

A centrifuge tube closure assembly removably attached to a centrifuge tube and including means for securing said assembly firmly to the centrifuge tube and means for venting air above the contents of the tube when said closure assembly is secured to the tube.

United States Patent Romanauskas [54] CENTRIFUGE TUBE CLOSURE ASSEMBLY [72] Inventor: William A. Romanauskas, Southbury,

Conn.

[73] Assignee: lvan Sorvall, lnc., Newton, Conn.

|22| Filed: Aug. 11,1970

[2i] Appl. No.: 62,921

- 52 11.5. CI. ..220/46 R, 220/55 AN 5 1 1 Int. Cl ..B65d 53 00 58 Field of Search ..220/46, 55 AN [451 Jan. 18, 1972 [56] References Cited UNITED STATES PATENTS 2,662,663 12/1953 Schmidt ..220/46 R 3,l48,l46 9/1964 Ashes et al ..220/46 R Primary Examiner-George T. Hall Att0rneyl. Jordan Kunik [57] ABSTRACT A centrifuge tube closure assembly removably attached to a centrifuge tube and including means for securing said assembly firmly to the centrifuge tube and means for venting air above the contents ofthe' tube when said closure assembly is secured to the tube.

15 Claims, 9 Drawing Figures mimmmem 3.635370 SHEET 1 [1F 2 mmmm 1 34 INVENTOR WILLIAM A. ROMANAUSKAS ATTORNEY PATENTEB JAM 8 m2- SHEET 2 [IF 2 IHI l \I FIG.5

IIIIHW INVENTOR WILLIAM A. ROMANAUSKAS BY A ATTORNEY r 1 CENTRIFUGE TUBE CLOSURE ASSEMBLY BACKGROUND OF THE INVENTION material and which are inserted into close-fitting receptacles in the centrifuge rotor, require closure components whichare secured to the tube and which are intended'to prevent said closures from becoming ejected from the tube while the rotor rotates at high speed. During high-speed rotation of the rotor, however, prior art closure elements very frequently become dislodged from their respective tubes whereby the contents.

thereof become discharged due to failure of the closure system. Prior art devices necessitate venting air trapped above the fluid contents of the tube through a tapped hole, followed by a post-filling operation by means of a syringe or the like through said hole, afterwhich the hole must be sealed by a separate plastic or elastomeric seal and set screw. It is most important that the trapped air volume be kept to a minimum since the liquid pressure is depended upon to support the tube wall and keep it from collapsing. In the present invention, the weight of the tube cap, augmented by centrifugal force, provides a' downward force component counteracting the hydrostatic fluid pressure.

SUMMARY OF THE INVENTION In order to overcome the defects and disadvantages of prior art devices, the apparatus herein includes novel means for removably securing the closure cap to the centrifuge tube by incorporating a combination of deformable washer and deformable O-ring which, together, form a secure frictional engagement between the closure and the tube. In some embodiments, the deformable washer of special beveled design may operate as n effective locking seal without the accompanying O-ring. The closure element has at least one or a plurality of lateral venting holes which communicate with a reduced-diameter portion of one of the closure elements whereby air above the surface of the tube conteritsis quickly and easily vented prior to the tightening of the closure assembly on the tube.

These and other novel features and advantages of the present invention will be described and defined'in the following specification and claims.

BRIEFDESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the assembled centrifuge tube and cap enclosure;

FIG. 2 is an exploded view, partially in section, partially broken away, and partially in elevation, of the component parts of the device shown in FIG. 1;

FIG. 3 is a top view of one of the cap elements of the closure assembly shown in FIG. 2;

FIG. 4 is a top view of the plug element of the closure assembly shown in FIG. 2;

FIG. 5 is a greatly enlarged fragmentary view of the beveled washer element shown in FIG. 2;

FIG. 6 is a greatly enlarged fragmentary central section view of the device shown in FIG. 1 prior to the tightening of the closure assembly upon the tube;

FIG. 7 is a fragmentary view of a portion of FIG. 6 showing the manner in which the washer and O-ring are deformed after the closure'assembly has been tighteneduponzthe tube;

FIG. 8 is a fragmentary view similar to FIG. 7 representing another embodiment of the invention where only a beveled washer is utilized without an O-ring for sealing and locking purposes; and

FIG. 9 is a fragmentary view of a section of the closure assembly and centrifuge tube disclosing an alternative embodiment of the invention herein, said view being comparable to a portion of the apparatus shown in FIG. 6, I

DESCRIPTION OF THE PREFERREDEMBODIMENT Referring now to the drawings in detail, the apparatus herein discloses a centrifuge tube 11 closed at the bottom end and open at the top. Said tube is made of a suitable transparent or translucent plastic material, insome embodiments, while in other embodiments it may be made of suitable sheet or extruded metal.

The closure assembly of the devicecomprises a circular plug 12 made of a suitable metal such as aluminum, or the like, said plug having a downwardly extending, integrally formed, annular skirt 13, the outside diameter of said skirt being slightly greater than the outside diameter of the main body of said plug. The peripheral surfaceof skirt 13 forms a very close sliding fit with the upper interior surface of tube 11. Formed on the upper portion of plug 12 isan integral circular stud portion 14 whose outside diameter is somewhat smaller than that of said plug, whereby a shoulder 16 is formed therebetween. Fonned in plug 12 and extending laterally therethrough is at least one or more spaced-apart ventholes 17, the outer ends of said holes terminating above the upper shoulder 18 of skirt 13. The interior ends vof holes 17 commu nicate with the top of cavity 19 formed .within skirt l3 and the lower portion of the main body of plug 12. See FIGS. 2, 6 and 7 Integrally formed centrally on the top of stud portion 14 is an upwardly extending threaded stub 21, two opposite sides of which are formed into flats 22. Cooperating with plug 12 is a circular cap element made of a suitable metal such as aluminum or the like, and generally designated 23, having a central aperture 24 through which stub 21 freely extends, said aperture having oppositely positioned flats 26 which cooperate with flats 22 to prevent relative rotation between cap 23 and plug 12. The top central surface of cap 23 is recessed to form an annular beveled slope27.

In some embodiments, flats 22 of stub 21 and flats 26 ofcap 23 may be replaced by components having square, hexagonal, octagonal contours or the like for preventing relative rotation between said cap and said stub. In other embodiments,flats of any contour may be completely eliminated where special tools or the like may be utilized for assembling the components of the tube closure.

Cap 23 has an integrally formed, downwardly extending annular skirt 28 whose inside diameter forms a close sliding fit with the outer peripheral surface of the top of tube 11, the upper end of said tube extending into and coming in contact with the upper end of an annular recess 29 in the interior of said cap. Fonned in the interior of cap 23 is a downwardly extending annular flange 31 which forms the inside bounds of annular recess 29.

Nested on shoulder 16 is a resilient O-ring 32 made of rubber, nylon, or the like. Resting on. top of O-ring 32 is a beveled, flexible and deformable washer 33, sometimes known as a Belleville washer, whose normal outside diameter is approximately equal to the inside diameter of tube 11. Washer 33 may be made of a suitable plastic material such as nylon, polyethylene, or the like.

In assembling the apparatus herein, O-ring 32 and washer 33, one above the other, are placed in position on shoulder 16 after which cap 23 is superimposed above-plug 12 and hex nut 34 is partially threadably engaged upon stub 21, as shown in FIG. 6. After materials to be centrifuged have initially been introduced into tube 11, the skirt portion 13 of plug 12 is inserted into said tube until the upper edge thereof abuts the upper surface of recess 29. During this action, any air that is located above the surface of the contents of tube 11 is expelled or vented through holes 17 by way of the reduced diameter main portion of plug 12 above shoulder 18 which is slightly spaced apart from the inner surface of tube 11. There exists sufficient venting space between flats 22 of stub 21 and flats 26 of aperture 24 to permit such venting to take place before the closure assembly is secured firmly in place. This venting action also takes place because O-ring 32 and washer 33, as yet uncompressed, are resilient and permit the upward bypassing of air through the aperture 24 of cap 23, and slightly loose threading engagement between stub 21 and nut 34.

The upper and lower identical surfaces 36 of nut 34 are beveled at the same angle as annular slope 27 of cap 23 so that a close sliding fit obtains therebetween regardless of whichever side of said nut is first threaded upon stub 21.

As nut 34 is tightened upon stub 21, plug 12 is drawn upwardly toward cap 23 whereby shoulder 16 and the bottom surface of flange 31 are urged together thereby causing between them the deformation of washer 33 and O-ring 32, as shown in FIG. 7. Cap 23 has a suitable annular recess 37 which slidably accommodates the upward movement of the stud portion 14. During this action, O-ring 32 which originally has a circular cross section, is deformed into an element having a substantially rectangular cross section whereby the internal and external diameters of said O-ring frictionally engage the interior surface of tube 1 1 and the external surface of stud portion 14. Also, washer 33 is deformed or flattened so that its original undeformed outside diameter is thereby increased to cause a frictional engagement between the outside diameter of said washer with the inside surface of said tube 11 and whose inside diameter is frictionally engaged with the outside surface of stud portion 14. The combined frictional engagement of O- ring 32 and washer 33 between the respective parts of tube 11 and plug 12 firmly lock the closure assembly and said tube together with a liquidtight seal whereby said assembly withstands the rigors of centrifugation without ejecting.

By utilizing a sealing washer 33 that is nonnally initially bevel-shaped, it is possible to use it both in conjunction with an O-ring 32 as well as alone without the O-ring, as shown in FIG. 8. The sealing washer serves to lock tube 11 to stud portion 14 of plug 12 with considerably less torque required to be applied on nut 34 than would be required with an O-ring alone or a flat washer.

When initially bevel-shaped washer 33 is flattened by the downward movement of flange 31, the outer diameter of washer 33 increases while the inside diameter thereof decreases. Thus, this type of washer performs the function both of sealing as well as locking by virtue of these properties. When washer 33 is used alone, without an O-ring as shown in FIG. 8, flange 31 of cap 23 is lengthened to compensate for the omitted O-ring.

When initially beveled washer 33 becomes flattened, a considerable mechanical advantage is achieved and, therefore, cap 23 is secured and locked in position on tube 11 with less axial force than is required by other seal arrangements. Another advantage is that if a screw thread is utilized to apply the requisite axial force, the clamping action will resist the screw torque required for the sealing action.

As may be observed in FIGS. 6 and 7, washer 33 acts as a backup ring preventing extrusion of O-ring 32 into the clearance space between annular flange 31 and the inside wall of tube 11. Also, said washer 33 prevents extrusion of O-ring 32 into the clearance space between annular flange 31 and the outer annular wall of stud portion 14 due to pressures generated during centrifugation. Since said clearances are necessary for manufacturing and assembly purposes, it is advantageous to ensure that extrusion of O-ring 32 into said clearance spaces is prevented.

An alternative arrangement for the closure assembly is illustrated in FlG. 9 wherein washer 33 is located below O-ring 32 in contrast to the relative positions of these components illustrated in FIGS. 2, 6 and 7. In the arrangement of FIG. 9, washer 33 is inverted compared to its position in FlG. 6. The embodiment shown in FIG. 9 may be desirable in certain types of closure assemblies where such an array may satisfy structural and operational requirements.

In some embodiments, the top of stub 21 may be provided with an axial threaded hole 41 tapped therein to accommodate a suitable threaded tool for inserting or removing the closure assembly relative to tube 11, or for holding said assembly fast while nut 34 is being tightened or loosened.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the principles and true spirit of the invention. The abstract" given above is for the convenience of technical searchers and is not to be used for interpreting the scope of the invention or claims.

I claim:

1. A tube closure comprising a tube open at one end, a plug removably insertable into the open end portion of said tube and extending at least partially into said tube, a cap detachably mounted on said plug and extending at least partially over the outer surface of said tube, a washer located between said plug and said cap in the interior of said tube, said washer being normally initially in beveled form, first means in the interior of said cap and second means on said plug to cause said washer to flatten whereby the outer diameter of said washer increased of said washer is decreased, said washer in the flattened condition exerting pressure simultaneously against said tube and said plug to lock said plug and said tube securely together.

2. A closure according to claim 1 wherein said first means comprises an annular flange and said second means comprises an annular shoulder which are urged together when said cap and said plug are urged together.

3. A closure according to claim 2 and further comprising a threaded stub on said plug and a nut engaging said stub for releasably causing said cap to be urged together with said plug.

4. A closure according to claim 1 and further comprising a resilient O-ring adjacent said washer, said O-ring being compressed between said first means and said second means to produce a liquidtight seal between said tube and said plug.

5. Apparatus according to claim 1 wherein a portion of said plug has a reduced diameter and is slightly displaced apart from the interior wall of said tube, and further comprising at least one laterally extending aperture in said plug in the area of said reduced-diameter portion, the inner end of said aperture communicating with the interior of said tube and the outer end of said aperture establishing communication with the atmosphere prior to the securing of said plug to said tube by the deformation of said washer.

6. Apparatus according to claim 1 wherein a portion of said plug has a reduced diameter and is slightly displaced apart from the interior wall of said tube, and further comprising at least one laterally extending aperture in said plug in the area of said reduced-diameter portion, the inner end of said aperture communicating with the interior of said tube and the outer end of said aperture establishing communication with the atmosphere prior to the securing of said plug to said tube by the deformation of said washer and said O-ring 7. Apparatus according to claim 1 and further comprising third means on said cap and fourth means on said plug cooperating with one another to prevent relative rotation between said cap and said plug.

8. Apparatus according to claim 7 wherein said third means comprises an aperture having at least one flat side in said cap, and said fourth means comprises a stub on said plug having at least one flat side, said stub extending freely through said aperture whereby said respective flat sides cooperate to prevent rotation of said cap and said plug relative to each other.

9. A closure assembly for a tube open at one end, comprising a plug removably insertable into the open end portion of said tube and extending at least partially therein, a cap detachably mounted on said plug and extending at least partially over the outer surface of said end portion of said tube,

first resilient means mounted between said plug and said tube, second means for releaseably urging said cap and said plug together to cause said first means to establish a fluidtight seal and lock between said assembly and said tube, a portion of the perimeter of said plug being of reduced diameter and spaced apart from the inner surface of said tube, and at least one venthole extending through said plug in the region of said reduced-diameter portion thereof and communicating with the interior of said tube for pen'nitting air above the contents of the tube to be vented therefrom prior to the operation of said second means to secure the closure assembly to said tube.

10. Apparatus according to claim 9 wherein a portion of said plug extending into the interior of said tube has an annular surface that forms a close sliding fit with the interior surface of said tube.

11. Apparatus according to claim 9 wherein said first means comprises an initially beveled washer, said washer being deformed under the action of said second means frictionally to engage the inner wall of said tube and an annular surface portion of said plug to effect a liquidtight lock and seal therebetween.

12. Apparatus according to claim 11 wherein said first means additionally includes a resilient O-ring adjacent said beveled washer, said O-ring also being deformed simultaneously with said washer to ensure a liquidtight seal between said assembly and said tube.

13. A tube closure comprising a tube open at one end, a plug removably insertable and extending partially into the open end portion of said tube, an annular recess ona portion of said plug, an O-ring in said annular recess, a beveled washer in said recess adjacent said O-ring, said O-ring and said washer being located in the interior of said tube, a cap detachably connectable to said plug, an annular recess in said cap accommodating the upper edge portion of said tube, and an annular ring in the interior of said cap which, when said cap is secured to said plug, urges together and causes the deformation of said O-ring and said washer in said recess to establish frictional engagement of both O-ring and washer with both said plug and the interior wall of said tube to establish a liquidtight seal therebetween.

14. A closure according to claim 13 wherein said washer prevents extrusion of said O-ring into adjacent clearance spaces between said plug and said tube.

15. A closure according to claim 13 wherein said washer is selectively positioned in either location above and below said O-ring. 

1. A tube closure comprising a tube open at one end, a plug removably insertable into the open end portion of said tube and extending at least partially into said tube, a cap detachably mounted on said plug and extending at least partially over the outer surface of said tube, a washer located between said plug and said cap in the interior of said tube, said washer being normally initially in beveled form, first means in the interior of said cap and second means on said plug to cause said washer to flatten whereby the outer diameter of said washer increased of said washer is decreased, said washer in the flattened condition exerting pressure simultaneously against said tube and said plug to lock said plug and said tube securely together.
 2. A closure according to claim 1 wherein said first means comprises an annular flange and said second means comprises an annular shoulder which are urged together when said cap and said plug are urged together.
 3. A closure according to claim 2 and further comprising a threaded stub on said plug and a nut engaging said stub for releasably causing said cap to be urged together with said plug.
 4. A closure according to claim 1 and further comprising a resilient O-ring adjacent said washer, said O-ring being compressed between said first means and said second means to produce a liquidtight seal between said tube and said plug.
 5. Apparatus according to claim 1 wherein a portion of said plug has a reduced diameter and is slightly displaced apart from the interior wall of said tube, and further comprising at least one laterally extending aperture in said plug in the area of said reduced-diameter portion, the inner end of said aperture communicating with the interior of said tube and the outer end of said aperture establishing communication with the atmosphere prior to the securing of said plug to said tube by the deformation of said washer.
 6. Apparatus according to claim 1 wherein a portion of said plug has a reduced diameter and is slightly displaced apart from the interior wall of said tube, and further comprising at least one laterally extending aperture in said plug in the area of said reduced-diameter portion, the inner end of said aperture communicating with the interior of said tube and the outer end of said aperture establishing communication with the atmosphere prior to the securing of said plug to said tube by the deformation of said washer and said O-ring
 7. Apparatus according to cLaim 1 and further comprising third means on said cap and fourth means on said plug cooperating with one another to prevent relative rotation between said cap and said plug.
 8. Apparatus according to claim 7 wherein said third means comprises an aperture having at least one flat side in said cap, and said fourth means comprises a stub on said plug having at least one flat side, said stub extending freely through said aperture whereby said respective flat sides cooperate to prevent rotation of said cap and said plug relative to each other.
 9. A closure assembly for a tube open at one end, comprising a plug removably insertable into the open end portion of said tube and extending at least partially therein, a cap detachably mounted on said plug and extending at least partially over the outer surface of said end portion of said tube, first resilient means mounted between said plug and said tube, second means for releaseably urging said cap and said plug together to cause said first means to establish a fluidtight seal and lock between said assembly and said tube, a portion of the perimeter of said plug being of reduced diameter and spaced apart from the inner surface of said tube, and at least one venthole extending through said plug in the region of said reduced-diameter portion thereof and communicating with the interior of said tube for permitting air above the contents of the tube to be vented therefrom prior to the operation of said second means to secure the closure assembly to said tube.
 10. Apparatus according to claim 9 wherein a portion of said plug extending into the interior of said tube has an annular surface that forms a close sliding fit with the interior surface of said tube.
 11. Apparatus according to claim 9 wherein said first means comprises an initially beveled washer, said washer being deformed under the action of said second means frictionally to engage the inner wall of said tube and an annular surface portion of said plug to effect a liquidtight lock and seal therebetween.
 12. Apparatus according to claim 11 wherein said first means additionally includes a resilient O-ring adjacent said beveled washer, said O-ring also being deformed simultaneously with said washer to ensure a liquidtight seal between said assembly and said tube.
 13. A tube closure comprising a tube open at one end, a plug removably insertable and extending partially into the open end portion of said tube, an annular recess on a portion of said plug, an O-ring in said annular recess, a beveled washer in said recess adjacent said O-ring, said O-ring and said washer being located in the interior of said tube, a cap detachably connectable to said plug, an annular recess in said cap accommodating the upper edge portion of said tube, and an annular ring in the interior of said cap which, when said cap is secured to said plug, urges together and causes the deformation of said O-ring and said washer in said recess to establish frictional engagement of both O-ring and washer with both said plug and the interior wall of said tube to establish a liquidtight seal therebetween.
 14. A closure according to claim 13 wherein said washer prevents extrusion of said O-ring into adjacent clearance spaces between said plug and said tube.
 15. A closure according to claim 13 wherein said washer is selectively positioned in either location above and below said O-ring. 